1. Field of the Invention
This invention relates to a water-soluble lubricant composition for a sleeve surface lubricating oil, an operating oil, a cutting oil, a rolling oil, a drawing oil, a press oil or the like. More particularly, this invention relates to a water-soluble lubricant composition which does not pollute the environment and has superior lubricity, metal corrosion preventing property, antifoaming property and antiseptic property.
2. Description of the Prior Art
A water-soluble lubricant composition for metal processing generally contains a mineral oil, a fat or oil, a carboxylic acid, an extreme pressure agent, a surfactant, an antifoaming agent, a metal corrosion preventing agent, an anti-oxidant, an antiseptic agent and the like and is diluted with water before use. The lubricant composition usually contains a nitrogen compound for giving it lubricity and the property of preventing metal corrosion in an aqueous system. Those nitrogen compounds include primary to tertiary alkanolamines, alkylamines, alkylarylamines, aralkylamines, cyclohexylamine, alkoxyalkylamines, diamines, addition products of alkylamine alkylene oxides, carboxylic acid amides and carboxylic acid alkylolamides (Japanese Patent Laid-open Nos. 7894/1980, 40400/1986, 235499/1986, 98696/1989, 201400/1989, 215889/1989, 242694/1989, etc.).
However, use of such water-soluble lubricant compositions for metal processing containing nitrogen compounds exerts a bad influence upon the earthly environment and contributes to environmental pollution.
Specifically, (1) although lubricants consisting of these compositions, after being used for metal processing, are subjected to waste water treatment and then discarded, these waste fluids still contain large amounts of nitrogen compounds. Therefore, discarding these waste fluids in waste water systems or sea areas results in eutrophication of rivers, lakes and seas thereby causing water pollution, red water and the like. Besides, (2) although it is theoretically possible to incinerate these waste fluids, in such a case, nitrogen compounds contained in the compositions are converted into the form of NOx and, when a sulfur compound is contained as an extreme pressure agent in the composition, the sulfur compound is converted into the form of SOx. These resulting compounds cause acid rain.
In addition, the conventional lubricant containing a nitrogen compound is unfavorable because it relatively easily foams, putrefies and corrodes non-ferrous metals. Especially when the lubricant is diluted with water and then supplied at high pressure to metallic parts to be processed, the lubricant significantly foams and causes problems such as its reduced performance and contamination of working environments.